ASPEN IN THE CENTRAL ROCKY MOUNTAIN REGION 
19 
to this fact as to any possible unpalatability. Blue spruce, which 
is stronger-flavored and has stiffer, sharper leaves, is frequently 
eaten. The blue spruce grows much more scatteringly than Engel- 
mann spruce, and at a lower elevation, where coniferous food is 
scarcer. 
In regions where rabbit damage is severe, the reduction of height 
growth, as shown in Table 10, materially increases the necessary rota- 
tion of conifers' and reduces the value of the product, thus handi- 
capping conifers in relation to aspen in forest management in many 
places (4). 
Table 10. — Effect of snowshoe rabbit injury on height growth of conifers 
Height 
Age 
Douglas fir 
White fir 
Alpine fir 
Normal 
Injured 
Normal 
Injured 
Normal 
Injured 
lOyears 
Feet 
0.6 
1.9 
5.1 
9.8 
14.4 
Feet 
0.6 
1.4 
2.5 
3.7 
6.4 
10.8 
15.6 
Feet 
0.6 
1.8 
3.8 
7.0 
12.5 
26.0 
Feet 
0.6 
1.8 
3.0 
4.6 
7.4 
13.5 
Feet 
0.6 
1.8 
4.0 
8.8 
16.8 
Feet 
0.6 
20 years 
30 years 
40years. . . 
1.6 
2.8 
4.2 
50years . 
6.0 
60 years 
9. 2 
70 years . ... . 
FIRE 
Although evidences of past fires in aspen are plentiful, and ex- 
tensive fires have run through the type within the memory of living 
men, they are extremely rare at the present time. The aspen leaf 
fall and debris is too scant to carry fire. Grazing has undoubtedly 
been chiefly responsible for reducing the fire hazard, as pockets in 
the aspen type inaccessible to livestock show rank undergrowth of 
tall, leafy grasses, such as Brwnas, Agropyron, and Stipa, as well as 
herbs, which are usually very scarce in the portions of the type 
grazed with ordinary intensity. Other evidence points to the same 
conclusion, that fires stopped at about the same time that grazing 
became heavy in the mountains. 
In connection with Meinecke's study of decay in aspen, it was 
found that in the stands in Ephraim Canyon, which are typical 
of central Utah, fire scars were plentiful. Owing to the difficulty 
of counting aspen rings with absolute accuracy, especially in partly 
decayed wood, it is improbable that fires occurred in every single 
year determined in this study. Nevertheless, the data indicate 
that there were fires in this locality in about 1770, 1800, 1816, 
1825, 1835, 1841, 1849, 1857, 1864 or 1865, and 1867 (this was a very 
large fire of incendrary origin, remembered by the older settlers). 
Following this, frequent fires until as late as 1875 are indicated by 
the fire scars. In 1884 another large fire occurred. The study re- 
vealed only 4 trees showing fire scars after that date (compared to 
43 in the period 1863 to 1873), 1 in each of the years 1889, 1894, 
1897, 1904. These results indicate that small, light fires occurred at 
intervals of 7 to 10 years in the same general region previous 
